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fusso
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How should I choose glass joint size?
I'm about to enter the "pro" glassware world, ie doing chemistry with round bottom flasks, condensers etc instead of test tubes and beakers. But I
don't know how to choose glassware joints for the apparatus  . Any tips?
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happyfooddance
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What amount of chemicals do you want to work with? Are you experimenting with chemical reactions or trying to produce large amounts of solvents. What
are your interests?
In general, for experimenting, smaller is better.
Smaller is also cheaper.
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ninhydric1
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If you are dealing with smaller quantities, quite a few people on this forum have ordered 14/20 distillation glassware. I, myself, own a 24/29
distillation setup, as well as a 24/29 separatory funnel, which is good for medium to large-scale reactions.
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Tsjerk
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Not knowing how much product you want to produce I would advise to buy a 14/20 distillation kit. This is already big enough to learn all possible
techniques you can with a distillation kit.
When you produce something that is worth weighing in milligrams it is what you will ever need.
I'm a big fanboy of microscale chemistry. If you can go big you can go small. The smaller your scale, the less space you need, fit the setup.
Temperature maintenance becomes easily doable when working on a milliliter scale, reactants become so easily spend you will run an extra optimization
run for the heck of it.
What it all comes down to is that the glass parts should be as small as you can get them; small is cheap, quick, easy, often.
If you are willing to invest, please invest in apparatuses supporting the micro scale future of your lab by buying a milligram scale, a small magnetic
steerer/heatermantle, a way to evaporate solvents (improvised rotovap).
The only good reason to start big is when you need a lot of kilos of your product. As long as you just want to test something anything bigger than ten
grams is throwing away money.
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Sulaiman
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Difficult choice
I have a cute NS10 Quickfit kit and a cheaper Chinese NS24 kit that I use most of the time.
I doubt that there is an 'ideal' size kit, but I'm fairly confident that NS10 is too small for a beginner, and NS24 may be slightly too large.
For all but the simplest distillations quite a bit of kit is required;
. glassware
. stand(s) and clamps
. heating (ideally with stirring)
. cooling (running water or a water/ice recirculating pump system)
All of this kit has to fit on your work area and into your storage area.
My NS24 kit takes up maybe 10x the storage space of similar NS10 kit 
I suggest that you look at prices from wherever you intend buying from,
(e.g. your local eBay) and compare overall costs for a COMPLETE kit,
including a suitable heating mantle, stands, cooling etc.
and
the larger the scale of your glassware, the larger your volume of solvents and product storage containers 
Last, but most contentious, is glassware quality.
Opinions differ: I love Quickfit, but I buy cheap Chinese 
[Edited on 15-4-2018 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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Bert
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I chose to go with 24/40, but my parameters are likely different from yours.
I was trained to believe the personal dangers of my area of chemical activities were more related to number of repetitions than the quantities
involved, beyond the fairly small ammounts required to seriously injure or kill me (I was specifically told at one point that beyond X ammount,
limiting batch size was purely a courtesy to the neighbors).
That is to say, if you're going to synthesize something to USE, make enough so you can run for some time before requiring another synthesis.
If you are experimenting and learning, go for the smaller sizes- It's probably safer, certainly more economical and easier on storage space.
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2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
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LearnedAmateur
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Most of my glassware is 14/23, my RBFs (100 and 250mL) and 50mL separatory funnel are 19/26 and I use an adapter to connect with my other glassware. I
also have a 60mL 24/29 fritted filter, again with an adapter in order to use it; AFAIK, you can’t really get smaller joint sizes for these so
that’s why I went with that size, since there needs to be room for the tube and plenty of air space to pull a vacuum.
My experimentations are on the millilitre scale, the max I usually have to deal with is about 200mL - for larger runs I’ll split it into smaller
batches but this is rare and only really involves generating salts which I’ll do in jars and other household containers. Helps with space too since
I only have a desk to perform all of my procedures.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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aga
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All of mine is 24/29.
Unless you have endless space and money, choose 24/29 or 14/23 and stick with it.
Amazing how many bits of glass build up over a short time.
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JJay
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It's hard to go wrong with N24. I slightly prefer 24/40 for adapters and 24/29 for flasks. Generally, an apparatus constructed entirely with 24/40
joints is more stable and requires less joint grease, but 24/29 joints are easier to get apart when stuck. 24/xx is generally compatible with other
24/xx, although you may encounter some occasional off pieces on things like non-addition sep funnels. 24/29 is generally the cheapest, and the flask
sizes can be anywhere from 25 mL to 10 L and probably larger or smaller (so you can do reactions on a 2.5 mL scale or a 5 L scale).
My largest flask is 3 L, and I have considered obtaining something larger, but that's big enough for most tasks that I want to do as a hobbyist. 2 L
is probably big enough for almost everything, really... once in a while I want to do something in extremely dilute conditions and wish I had
bucket-size flasks and tanker trucks of solvent, but usually it is pretty easy to scale things down as long as the quantities aren't so tiny that you
can't avoid massive mechanical losses. There are things that I use 20 L buckets for, and if I had massive flasks, I would probably use them, but I'm
not even sure where I would store something like that....
I use 14/10 microscale glassware with screw fittings for the really small stuff. It is largely compatible with 14/20, and I use 14/20 replacement
parts when possible since they are much cheaper than 14/10.
I have noticed that most of the top-notch YouTube chemists (in particular, Nile Red, Nurdrage, and Chem Player) use a range of joint sizes with
adapters. I think Doug's Lab belongs in that echelon also, and he seems to use mainly N24 (pretty sure UC235 did too).
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fusso
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Quote: Originally posted by JJay  | It's hard to go wrong with N24. I slightly prefer 24/40 for adapters and 24/29 for flasks. Generally, an apparatus constructed entirely with 24/40
joints is more stable and requires less joint grease, but 24/29 joints are easier to get apart when stuck. 24/xx is generally compatible with other
24/xx, although you may encounter some occasional off pieces on things like non-addition sep funnels. 24/29 is generally the cheapest, and the flask
sizes can be anywhere from 25 mL to 10 L and probably larger or smaller (so you can do reactions on a 2.5 mL scale or a 5 L scale).
My largest flask is 3 L, and I have considered obtaining something larger, but that's big enough for most tasks that I want to do as a hobbyist. 2 L
is probably big enough for almost everything, really... once in a while I want to do something in extremely dilute conditions and wish I had
bucket-size flasks and tanker trucks of solvent, but usually it is pretty easy to scale things down as long as the quantities aren't so tiny that you
can't avoid massive mechanical losses. There are things that I use 20 L buckets for, and if I had massive flasks, I would probably use them, but I'm
not even sure where I would store something like that....
I use 14/10 microscale glassware with screw fittings for the really small stuff. It is largely compatible with 14/20, and I use 14/20 replacement
parts when possible since they are much cheaper than 14/10.
I have noticed that most of the top-notch YouTube chemists (in particular, Nile Red, Nurdrage, and Chem Player) use a range of joint sizes with
adapters. I think Doug's Lab belongs in that echelon also, and he seems to use mainly N24 (pretty sure UC235 did too).
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@JJay whats N24?
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fusso
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Thx for the info. I'd like to go with ~5-10g scale for synthesis and ~150ml solvent distillation but I actually want to know what the numbers like
14/20 & 24/29 mean? And compatibility issues like JJay said "24/xx is generally compatible with other 24/xx". Thats my main trouble when I'm
considering sizes.
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JJay
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The first number is the width in millimeters at the widest point. The second number is the length of the joint in millimeters. Standard taper is 1:10
for ground glass stoppers (also most lab corks and rubber stoppers). N24 is a notation I've seen used to describe 24/40 and 24/29 joints.
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fusso
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| Quote: Originally posted by JJay | | The first number is the width in millimeters at the widest point. The second number is the length of the joint in millimeters. Standard taper is 1:10
for ground glass stoppers (also most lab corks and rubber stoppers). N24 is a notation I've seen used to describe 24/40 and 24/29 joints.
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and what's 1:10?
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JJay
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10%
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fusso
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Slope of the joint // to the ___(?) axis right?
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fusso
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For the sep funnel, should I use conical or cylindrical?
Should I use one with narrower tip at the stopcock end or one with ground joint end like this img? https://www.aliexpress.com/item/1000ml-24-40-Glass-Separator...
Should I use PTFE or glass stopcock?
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Plunkett
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It is difficult to see in the picture, but if the separatory funnel you linked is like the one I bought from China (seller sam10086, a Deschem
distributor I believe), there is a narrower tip inside of the ground joint, like the ones without the jointed end. I would go for the funnel with the
ground glass joint end because you can also use it as an addition funnel. The joint does get in the way sometimes but I think overall it is more
versatile.
[Edited on 15-4-2018 by Plunkett]
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LearnedAmateur
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Strictly, the bulbous design is a separatory and the straight tube is an addition funnel but they’re very often used interchangeably - I myself have
the straight tube since what matters is the stopcock and the narrow point at the end where layer separation can be more tightly controlled. Mine also
has a ground joint after the stopcock, but it shouldn’t matter if you don’t mind holding it for a separation, but if you need to do a long
addition for instance (dropwise or a trickle) then get a jointed tube so you’re not holding it for hours or minutes. Also don’t forget to pressure
equalise on either side if using a jointed funnel otherwise air will bubble through or the flow will completely stop!
Both PFTE and glass are just as good as one another IME, but I prefer the former because it is less likely to become frozen, such as if you have a
thin layer of some liquid trapped and it solidifies or you are dealing with hot solutions in some circumstances. Both should be highly resilient to
chemical attack though, so it’s up to your discretion - how tightly the screw is done up will mostly determine what I mentioned in the last
sentence.
This is the design I go with for all of my addition and separation needs, I stand by it. Perfect size for everything I’ve needed it for too.
[Edited on 15-4-2018 by LearnedAmateur]
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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JJay
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It means for every centimeter, the joint tapers by a millimeter.
I don't think the shape of a sep funnel matters much, but I prefer conical for actual sep funnels and cylindrical for addition funnels... the
cylindrical shape makes it easier to estimate the volume remaining in the funnel. I can't think of many situations where a PTFE stopcock isn't better
than a glass one... perhaps when handling hot liquids that could cause the PTFE stopcock to jam and bind or handling really hot liquids that could
destroy the stopcock... but how often do you handle hot liquids in a sep funnel.... Glass is fine for most purposes but needs to be greased, so your
product will probably be contaminated with fluorinated silicone grease, and glass can be attacked by strong alkali... at ordinary temperatures, PTFE
is pretty inert to almost every substance you're likely to encounter unless you're doing something exotic like home fluoropolymer chemistry (for
example, apparently, perfluorinated decalin can dissolve PTFE at 350 C). Glass is somewhat easier to clean than PTFE in my opinion, but that's rarely even a minor
issue with stopcocks.
You might save a few bucks by getting a sep funnel without a ground glass joint below the stopcock, but when I bought my second 1L sep funnel (a sep
funnel is a pretty important piece of equipment, and no one wants to wait a month for a new one), I bought one with a ground glass joint below the
stopcock. Actually, I bought that same sep funnel, and it is high quality and came with a standard stopper with a cool bulbous flare handle. It can
work just fine as an ordinary sep funnel. Just don't attach the joint directly to an apparatus to drain the contents unless you have some way to
relieve pressure (draining it into a beaker is fine, but draining it directly into an RBF is probably not a good move).
I personally almost never use non-equalizing addition funnels, but that sep funnel can double as a non-equalizing addition funnel in a pinch. I hardly
ever use mine because I have a well-used GG-17 funnel with a nonstandard stopper that works fine for separations, and I intend to continue using it
until it breaks, with the Deschem funnel as a backup. I also have a cylindrical pressure-equalizing addition funnel that I use for most controlled
additions.
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S.C. Wack
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24/40 is big for your scale. 19/22 is a great size; easier in many ways to work with than larger pieces.
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fusso
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Will a piece of glassware of specific size eg 500ml round bot flask have specific joint size eg 24/29? Or are there a few joint sizes to choose from
eg 19/22 & 24/29?
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DavidJR
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Within reason you can buy lots of combinations of flask size/joint size. However larger volume flasks will be more readily found with the larger
joints. E.g. good luck finding a 2L flask with a 14/23 joint...
I went for 24/29 in large part because you can get a wide range of glassware easily and cheaply as it's a very popular size. However I think the most
important thing is to pick one size and stick to it, that way you have the most flexibility.
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Dr.Bob
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US sizes are typically 14/20, 19/22, 24/40, and 29/42, which are ideal for scales of 10-250 ml, 50-500 ml, 100-1000 ml, and 250-25L scales. So for
most home chemists, I recommend 14/20 as a starter, and then 24/40 or larger if you need to go bigger, for solvent distillations, and bigger
reactions. 24/40 is the easiest size to find parts for, followed by 14/20, which is less common, but usually cheaper as smaller scale. 19/22 is
hard to find cheap parts for in the US.
Non-US countries have other various joint lengths, like 14/23, 14/29, etc, but the taper is the same, so often they interchange OK.
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XeonTheMGPony
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All so first select a size range, then research what is the most common in that range then select that.
I do large volume runs when I do any thing, as Bert n I share commonality, and the rules of numbers come in to play, the more you do some thing the
more the odds of some thing bad happening, so it is better to do one big run very care fully then doing allot of small runs!
So I went with 24/40 since it meets my scale requirements and it is the most common out there. That was my selection method.
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Dr.Bob
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That makes sense. If you are looking for 24/40 parts, there are many people selling them on Amazon, Ebay, and other spots. I also have lots of 24/40
accessories, like addition funnels (with and w/o equalization arms), Dean- Stark Traps, various adapters, condensers, and much more.
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